1. Field of the Invention
The present invention relates to the technical field of a node device and the like in a tree type network system or a broadcast system and especially, relates to a technical field of a tree type network system, a node device and the like of the system, and a connection administration device for managing connection status between a broadcast station and each of node devices and connection administration method in a broadcast system in which a node device itself decides connection status in consideration of device information of each other.
2. Discussion of the Related Art
In recent years, in a network environment technology such as the internet, a content data distribution delivery technique which enables delivery of content data between user terminal devices is especially proposed.
This system is a so-called peer-to-peer type content data delivery system. Unlike a client server type content delivery system, transmission and reception of stream delivered content data is performed between node devices as clients. When a node device participates in the system, the node device is connected to any of node devices which configure the system to receive content data, and the data is transferred (relayed) to a lower stream (lower hierarchy level) node device. Moreover, each of the node devices can leave the network arbitrarily or can be connected to an upper stream (upper hierarchy level) node device according to a predetermined condition.
In general, such a topology (connection relation) is managed by a dedicated server and a node device which newly participates in the system acquires location information of an already-participated node device, which is to be connection destination, (for example, IP address and port number) from the dedicated server to be connected to the already-participated node device. That is, the dedicated server decides a node device to which a node device newly participating in the system is to be connected to receive delivery of content data.
On the other hand, as disclosed in Patent Document 1, a distribution administration type network file system in which each of node devices has topology information for recognizing network connection relation, and without necessity of a dedicated server as mentioned above, each node device is connected to a node device recognized by the topology information has been proposed.    Patent Document 1: Japanese Published Unexamined Patent Application No. 2003-169089